Big-hitting Karlovic was also on the end of an upset, losing his seventh successive match by going down 6-3 6-4 to Lucas Pouille in just under 61 minutes.

The Croatian second seed produced 10 aces but was less efficient on his first serve than the 22-year-old Frenchman, who set up a quarter-final clash with Paolo Lorenzi following the Italian's 6-2 6-0 win against Taro Daniel.

After beating Illya Marchenko 7-5 6-2, Federico Delbonis is now the highest seed remaining in the competition, while defending champion Guillermo Garcia-Lopez remains in contention following the Spaniard's 6-3 6-3 triumph over Kyle Edmund.